HD6413007F20 Datasheet, PDF (505/798 Pages) Renesas Technology Corp – Hardware Manual Renesas 16-Bit Single-Chip Microcomputer H8 Family/H8/300H Series

13. Serial Communication Interface
• Transmitting Serial Data (Synchronous Mode): Figure 13.16 shows a sample flowchart for
transmitting serial data and indicates the procedure to follow.
Initialize
Start transmitting
Read TDRE flag in SSR
(1) (1) ^{SCI initialization: the transmit data output}
function of the TxD pin is selected
automatically.
(2) SCI status check and transmit data write:
read SSR, check that the TDRE flag is 1,
(2)
then write transmit data in TDR and clear
the TDRE flag to 0.
TDRE = 1
No
Yes
Write transmit data in TDR
and clear TDRE flag to 0 in SSR
(3) To continue transmitting serial data: after
checking that the TDRE flag is 1, indicating
that data can be written, write data in TDR,
then clear the TDRE flag to 0. When the
DMAC is activated by a transmit-data-empty
interrupt request (TXI) to write data in TDR,
the TDRE flag is checked and cleared
automatically.
All data transmitted?
No
(3)
Yes
Read TEND flag in SSR
No
TEND = 1
Yes
Clear TE bit to 0 in SCR
<End>
Figure 13.16 Sample Flowchart for Serial Transmitting
In transmitting serial data, the SCI operates as follows.
• The SCI monitors the TDRE flag in SSR. When the TDRE flag is cleared to 0, the SCI
recognizes that TDR contains new data, and loads this data from TDR into TSR.
Rev.5.00 Sep. 12, 2007 Page 475 of 764
REJ09B0396-0500